Highly Conductive Polymer Anodes as Replacements for Inorganic Materials in High-Efficiency Organic Light-Emitting Diodes

摘要

During the last several years, organic light-emitting diodes (OLEDs) characterized by potentially high efficiencies and long lifetimes have attracted the interest of both the scientific and industrial communities, as they are a promising new route to energy-efficient, high-quality displays and large-area lighting applications. The first organic light-emitting materials were fluorescent emitters in which only singlet excitons contributed to the overall device efficiency. Highly efficient light-emitting materials based on phosphorescent emitters, which also use the radiative decay of triplet excitons, were developed, and these OLEDs performed well above, for example, incandescent lighting sources. Since the beginning of OLED development, indium tin oxide (ITO) has been the most commonly used anode material. The ITO work function is typically in the range 4.5-4.7 eV and depends on the method of ITO preparation and its surface treatment. This range of values is somewhat low for efficient hole injection in typical organic hole-transport materials.